1. Field of the Invention
The present invention relates generally to getters or filtration media for improved removal of pollutants from the environment and more particularly to high surface area materials having functional molecular monolayers assembled thereon.
2. Description of the Prior Art
Heating, ventilation, and air conditioning (HVAC) systems are installed in modern buildings to enhance comfort. Those systems not only provide warm or cool air, as needed to maintain room temperature within desired ranges, but also supply fresh air to dilute and replace ambient room air that becomes polluted by human habitation and other sources, such as chemical release from pressed woods, carpets, paint, copy machines, and the like. An increased awareness of chemical pollutants in the environment has resulted in the critical evaluation of air quality in commercial, residential, and industrial structures. Incidents of sick-building syndrome and reports of multiple chemical sensitivity (MCS) as result of exposure to common indoor air pollutants has resulted in action at the federal government level. Current standards of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) set in 1989 require a minimum fresh air ventilation rate of 7.1 liters/second/person (15 cfm/person) for general building and 9.4 liters/second/person (20 cfm/person) for office buildings.
Adequate exhausting of pollutants for a room or building is necessary and is accomplished by diluting the pollutants inside with fresh air from the outside, while drawing some air out of the room through a return duct. Increasing the air exchange rate results in a dramatic drop in the energy efficiency of buildings. This is reflected in increased energy demands and thus operating costs. Consequently, it is necessary to achieve a greater degree of removal and isolation of chemical pollutants without resorting to large air volume exchanges that involve increased energy demands and high operating costs.
Positioning a filtration device directly in the path of the air flow prior to introducing or injecting air into a room through a duct outlet has been found to be a reasonably effective way to achieve the removal of pollutants. However, there is still a need for substantial further improvement.
There have been some apparatus and methods developed for the removal of pollutants from both, moving streams of air and water. For example, the standard state-of-the-art filtration medium is high surface area (HSA) activated carbon. Many different types of activated carbons with varied internal pore sizes, surface areas, and active surface sites are commercially available. Activated carbons are extensively used to remove a variety of pollutants from both air and water systems, as discussed by Adamson, Physical Chemistry of Surfaces, Wiley, 1982. However as discussed by Ramanathan, Proceedings of the ASHRE/SOEH Conferences IAQ89, p. 33, April 1989, a disadvantage of activated carbon is that although it is capable of reducing high concentrations of many common indoor pollutants it becomes increasingly ineffective as the concentration of the pollutant drops. Even with surface areas exceeding 1000 m.sub.2 /g, activated carbon tends to show very early breakthrough behavior in normal size filter beds requiring many air passes to retain its effectiveness. If improvements were made at the molecular level of filtration media, for trapping pollutants present at low levels, indoor air quality would be vastly improved while maintaining the energy efficiency of the building.